1. Field of the Invention
The present invention relates to a servo amplifier having a cooling structure including a heat sink.
2. Description of the Related Art
A common servo amplifier is provided with a cooling means for cooling a heat source in a servo amplifier, such as a heat sink and a fan motor. In order to enhance the cooling effect, surface area or volume of the heat sink is increased, rotational speed of the fan motor is increased, or a heat conducting member is used to conduct heat to a cooling structure arranged at a position distant from the heat source.
JP-A-2009-111310 discloses a cooing method for cooling electronic equipment by interposing a heat conducting member between a heat source and a metallic cabinet for accommodating the electronic equipment.
In order to increase the surface area or volume of the heat sink, it is necessary to provide a sufficiently large space around the heat source. However, space available in the housing of the servo amplifier is often predetermined and limited. Therefore, improvements in a heat dissipating effect of the heat sink by its design change are limited. In the case where a rotational speed of the fan motor is increased to enhance the heat dissipating effect, life of the fan motor tends to be shortened as the rotational speed is higher.
In the case where the technique disclosed in JP-A-2009-111310, i.e., conducting heat from a heat source to a cooling structure arranged distant from the heat source through a heat conducting member, is applied to a servo amplifier including a power semiconductor which produces a large amount of heat generation, since a distance between the heat source and a cabinet is relatively large, it is difficult to achieve a sufficient cooling effect. In this case, it is necessary to provide an expensive cooling means such as a heat pipe as a heat conducting member. This leads to an increase in cost of the servo amplifier.
Accordingly, there is a need for an inexpensive servo amplifier including a cooling structure having an efficient heat dissipation effect.